IOWA ACADEMY OF SCIENCES. 
149 
fore, that such a method would be a combination of the 
two already mentioned, the reduction of a chlorate by a 
metal and a more efficient one than zinc, and the reduction 
by ferrous sulphate. 
To carry out the method a weighed amount of pure potas- 
sium chlorate or a measured amount of chloric acid was 
placed in a small flask with about 50 c.c. of pure sulphuric 
acid having a concentration of about 10 per cent, and an 
excess of “card teeth”, used in most laboratories. In some 
of the experiments recorded below, the flask was fitted 
with a delivery tube, dipping into water, the purpose being 
to prevent the possible loss of hydrochloric acid, but this 
precaution was found to be wholly unnecessary. At first 
ferric salt is formed and the liquid becomes yellowish- 
brown, but the dissolved iron is soon reduced and the solu- 
tion becomes colorless or slightly green. If all the chlorate 
is dissolved at the beginning, the disappearance of the yel- 
low color may be taken to mark the end of the reduction, 
which requires at room temperature about one hour. No 
doubt the reduction could be hastened by heating, if pre- 
cautions were taken to prevent the loss of any hydrochloric 
acid. As might naturally be expected the method serves 
quite as well for the determination of bromic acid and 
bromates as for chloric acid and chlorates, and two deter- 
minations of bromic acid in potassium bromate are given 
below. 
After the reduction was completed, the solution was 
made up to a definite volume, and portions of it were 
titrated with N / 20 silver nitrate. Usually, an excess of 
silver was added before the iron was oxidized to the ferric 
condition, to serve as the indicator, by the addition of an 
excess of nitric acid. There seems, however, to be little 
danger of the loss of chlorine, if the nitric acid is added 
before the silver. 
The following are results obtained by the method de- 
scribed, the amount of silver required in the titrations 
being calculated to chloric or bromic acid: 
